Patch "powerpc/64s: Allow control of RFI flush via debugfs" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/64s: Allow control of RFI flush via debugfs

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-64s-allow-control-of-rfi-flush-via-debugfs.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Michael Ellerman <[email protected]>
Date: Tue, 16 Jan 2018 22:17:18 +1100
Subject: powerpc/64s: Allow control of RFI flush via debugfs

From: Michael Ellerman <[email protected]>

commit 236003e6b5443c45c18e613d2b0d776a9f87540e upstream.

Expose the state of the RFI flush (enabled/disabled) via debugfs, and allow it to be enabled/disabled at runtime.

eg: $ cat /sys/kernel/debug/powerpc/rfi_flush
1
$ echo 0 > /sys/kernel/debug/powerpc/rfi_flush $ cat /sys/kernel/debug/powerpc/rfi_flush 0

---
 arch/powerpc/kernel/setup_64.c |   30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

@@ -39,6 +39,7 @@
 #include <linux/memory.h>
 #include <linux/nmi.h>
 
+#include <asm/debugfs.h>
 #include <asm/io.h>
 #include <asm/kdump.h>
 #include <asm/prom.h>

@@ -935,6 +936,35 @@ void __init setup_rfi_flush(enum l1d_flu
 		rfi_flush_enable(enable);
 }
 
+#ifdef CONFIG_DEBUG_FS
+static int rfi_flush_set(void *data, u64 val)
+{
+	if (val == 1)
+		rfi_flush_enable(true);
+	else if (val == 0)
+		rfi_flush_enable(false);
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int rfi_flush_get(void *data, u64 *val)
+{
+	*val = rfi_flush ? 1 : 0;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_rfi_flush, rfi_flush_get, rfi_flush_set, "%llu\n");
+
+static __init int rfi_flush_debugfs_init(void)
+{
+	debugfs_create_file("rfi_flush", 0600, powerpc_debugfs_root, NULL, &fops_rfi_flush);
+	return 0;
+}
+device_initcall(rfi_flush_debugfs_init);
+#endif
+
 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	if (rfi_flush)

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/powerpc-simplify-module-toc-handling.patch queue-4.4/powerpc-64s-simple-rfi-macro-conversions.patch queue-4.4/powerpc-64-fix-flush_-d-i-cache_range-called-from-modules.patch queue-4.4/powerpc-64-add-macros-for-annotating-the-destination-of-rfid-hrfid.patch queue-4.4/powerpc-pseries-add-h_get_cpu_characteristics-flags-wrapper.patch queue-4.4/powerpc-64s-allow-control-of-rfi-flush-via-debugfs.patch queue-4.4/powerpc-powernv-check-device-tree-for-rfi-flush-settings.patch queue-4.4/powerpc-64s-convert-slb_miss_common-to-use-rfi_to_user-kernel.patch queue-4.4/powerpc-64s-support-disabling-rfi-flush-with-no_rfi_flush-and-nopti.patch queue-4.4/powerpc-64-convert-the-syscall-exit-path-to-use-rfi_to_user-kernel.patch queue-4.4/powerpc-bpf-jit-disable-classic-bpf-jit-on-ppc64le.patch queue-4.4/powerpc-64s-add-support-for-rfi-flush-of-l1-d-cache.patch queue-4.4/powerpc-pseries-query-hypervisor-for-rfi-flush-settings.patch queue-4.4/powerpc-fix-vsx-enabling-flushing-to-also-test-msr_fp-and-msr_vec.patch queue-4.4/powerpc-64-convert-fast_exception_return-to-use-rfi_to_user-kernel.patch queue-4.4/powerpc-64s-wire-up-cpu_show_meltdown.patch